Rainbow Thrower

A fascinating but simple toy for kids and adults that uses an item from an unexpected source: military surplus.

It was probably close to 50 years ago that I bought my first surplus tank prism taken from a periscope housing. I remember being amazed at the colorful spectrum it projected across a room when placed in direct sunlight. A few years ago I “rediscovered” some of these precisely ground pieces of glass and decided to build a functional cradle that allows for a more controlled aiming of the “rainbow.”

It is possible to use a prism by just standing it on end on a sunny windowsill, but you will get much better results by constructing a stand that will allow for horizontal mounting and making fine adjustments to compensate for the daily changes in the sun’s position in the sky.

Before we begin, there are a few things you should know about these surplus prisms. They are available in three configurations: mounted in the original metal housing, one side silvered (a mirror coating), and plain unsilvered. You want the plain ones. You can usually save a few bucks by purchasing one in the original housing, but remember these were built under contract from Uncle Sam for use in military combat vehicles. To say they are ruggedly mounted is an understatement. Trying to extract one may result in the invention of new swearwords and a broken prism.

To Read the Full Story, Subscribe or Sign in

By purchasing a full subscription, you will gain access to all of Woodcraft Magazine's online publications as well as the printed publication mailed bi-monthly!